1. Field of the Invention
The present invention relates to a device for adjusting height of an armrest for an office chair.
2. Prior Art
There has been proposed a device for adjusting height of an armrest for a chair, e.g. by Japanese Patent Application No. 9-234134, which comprises a hollow support, a longitudinally extending adjusting slit disposed on the support, receiving/supporting portions longitudinally disposed at the adjusting slit, a longitudinally extending receiving/supporting cylinder for use in an armrest, an operating lever swingably mounted on the receiving/supporting cylinder, and a pin disposed on a distal end of the operating lever, and selectively engaged with the receiving/supporting portion.
According to the prior art, the operation of adjusting the height of the armrest is carried out by engaging the operating lever with a notch (slit) disposed on the receiving/supporting cylinder, and pressing the operating lever protruding from the notch toward the support; thereby causing the operating lever to necessarily partially protrude from the receiving/supporting cylinder, which provides problems related to an exterior view and a decency of the device. Further, the height of the armrest is held using an urging force of a plate spring against the operating lever, which provides disadvantages that the function of holding the height of the armrest is lowered with the aged deterioration of the plate spring, and that the height of the armrest is difficult to be held when the plate spring receives a force stronger than its resilient force from above.